242 
BRITISH PHARMACEUTICAL CONFERENCE. 
quinine; nearly all are proposed for the indication of quinine only, or its detec¬ 
tion when mixed with other substances. 
The polariscope tests of Bouchardat and Pasteur, and the fluorescent test of 
Professor Stokes, require too much study and practice to come into general use 
for qualitative analysis among manufacturers and retailers. 
The same remarks apply to the exquisitely beautiful experiments of Dr. W. 
B. Herapath. It is quite true that to the expert the iodine test will detect the 
presence of a very minute portion of quinine, quinidine, or cinchonidine, yet it 
requires considerable experience with an expensive polarizing microscope, with 
great consumption of time, to give good results, when only a minute quantity is 
operated on. 
The chlorine and ammonia test of Brande, and the chlorine test of Pelletier, 
will not distinguish always between quinine and quinidine. 
The presence of so much water and ammonia is detrimental to the British 
Pharmacopoeia test, which is anything but a good modification of Liebig’s 
original one. 
Prom these remarks it will be apparent that a good qualitative test for de¬ 
tecting the several cinchona alkaloids in an unknown mixture is a desideratum. 
From a considerable series of experiments it appears that these conditions may 
be amply fulfilled by either of the two following methods. 
The first is a modification of that proposed by Liebig. 
Into a glass tube or bottle put ten grains of the suspected salt, dissolve in 
ten minims of dilute sulphuric acid and GO minims of distilled water ; to this 
add 150 minims of pure sulphuric ether, three minims of alcohol, and 40 minims 
of a solution of hydrate of soda (1 part to 12 parts). Agitate well and lay 
aside for twelve hours, when if the slightest trace of quinidine, cinchonine, or 
cinchonidine be present, they will be seen at the line of separation between the 
ether and solution of sulphate of soda. 
If only a small percentage of quinidine be present, it will appear as an oily 
substratum, appearing under the lens as dust from the minuteness of its parti¬ 
cles. Cinchonine will appear more decidedly crystalline. With a little prac¬ 
tice, the eye will easily distinguish which of the alkaloids is deposited. 
This will detect a much less quantity of quinidine than the Pharmacopoeia 
test. In the latter the ether dissolves a greater portion of the quinidine, while 
the dilute ammoniacal solution of sulphate of ammonia is an actual solvent un¬ 
less great care be taken to add no more ammonia than will exactly precipitate 
the alkaloids, which is often difficult and tedious. 
The second method proposed is the one most generally used by the author, 
and which is perhaps the easiest and most trustworthy of any hitherto sub¬ 
mitted. The reagent is sulphocyanide of potassium. 
Into an ounce of distilled water drop ten drops of dilute sulphuric acid (Bri¬ 
tish Pharmacopoeia 1 f-)- To tins add 14 grains (or as much as will saturate the 
acid) of the suspected salt. Filter through paper, and to a little of the filtered 
solution add a few drops of the solution of sulphocyanide of potassium (180 
grains in 1| ounces of water). An immediate precipitate of the several alka¬ 
loids takes place, each of which, as seen by the sketches, is distinct and cha¬ 
racteristic. 
If quinine, quinidine, and cinchonine be present they will all be seen on the 
slide distinct from each other, becoming more so every minute. 
A very good plan is to place a very small drop on a glass slip and to put an¬ 
other of the sulphocyanide by its side. Over both place a piece of thin glass, 
which will cause the drops to touch. Examine the line of junction under a 
quarter-inch lens, when the crystals are seen and may be readily recognized. 
By this method of a grain of quinidine or cinchonine may easily be de¬ 
tected. 
